/*
 *  V4L2 video capture example
 *
 *  This program can be used and distributed without restrictions.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <getopt.h>             /* getopt_long() */

#include <fcntl.h>              /* low-level i/o */
#include <unistd.h>
#include <errno.h>
#include <malloc.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/ioctl.h>

#include <asm/types.h>          /* for videodev2.h */

#include <linux/videodev2.h>

#define CLEAR(x) memset (&(x), 0, sizeof (x))

typedef enum {
	IO_METHOD_READ,
	IO_METHOD_MMAP,
	IO_METHOD_USERPTR,
} io_method;

struct buffer {
    void *                  start;
    size_t                  length;
};

static char *dev_name = NULL;
static io_method io	= IO_METHOD_MMAP;
static int fd = -1;
struct buffer *buffers = NULL;
static unsigned int n_buffers = 0;

static int fb_fd = -1;
static FILE *save_fd = NULL;

static void
errno_exit(const char *s)
{
    fprintf (stderr, "%s error %d, %s\n", s, errno, strerror (errno));
    exit (EXIT_FAILURE);
}

static int
xioctl(int fd, int request, void *arg)
{
    int r;

    do r = ioctl (fd, request, arg);
    while (-1 == r && EINTR == errno);

    return r;
}

static void
process_image(const void *p, size_t length)
{
    fputc ('.', stdout);
	fwrite(p, sizeof(char), length, save_fd);
    fflush (stdout);
}

static int read_frame(void)
{
    struct v4l2_buffer buf;
	unsigned int i;

	switch (io) {
	case IO_METHOD_READ:
        if (-1 == read (fd, buffers[0].start, buffers[0].length)) {
            switch (errno) {
            case EAGAIN:
                return 0;

			case EIO:
				/* Could ignore EIO, see spec. */

				/* fall through */

			default:
				errno_exit ("read");
			}
		}

        process_image (buffers[0].start, buffers[0].length);

		break;

	case IO_METHOD_MMAP:
		CLEAR (buf);

        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_MMAP;

        if (-1 == xioctl (fd, VIDIOC_DQBUF, &buf)) {
            switch (errno) {
            case EAGAIN:
                return 0;

			case EIO:
				/* Could ignore EIO, see spec. */

				/* fall through */

			default:
				errno_exit ("VIDIOC_DQBUF");
			}
		}

        assert (buf.index < n_buffers);

        process_image (buffers[buf.index].start, buffers[buf.index].length);

		if (-1 == xioctl (fd, VIDIOC_QBUF, &buf))
			errno_exit ("VIDIOC_QBUF");

		break;

	case IO_METHOD_USERPTR:
		CLEAR (buf);

        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory = V4L2_MEMORY_USERPTR;

		if (-1 == xioctl (fd, VIDIOC_DQBUF, &buf)) {
			switch (errno) {
			case EAGAIN:
				return 0;

			case EIO:
				/* Could ignore EIO, see spec. */

				/* fall through */

			default:
				errno_exit ("VIDIOC_DQBUF");
			}
		}

		for (i = 0; i < n_buffers; ++i)
			if (buf.m.userptr == (unsigned long) buffers[i].start
			    && buf.length == buffers[i].length)
				break;

		assert (i < n_buffers);

        process_image ((void *) buf.m.userptr, buf.length);

		if (-1 == xioctl (fd, VIDIOC_QBUF, &buf))
			errno_exit ("VIDIOC_QBUF");

		break;
	}

	return 1;
}

static void mainloop(void)
{
	unsigned int count;

    count = 100;

    while (count-- > 0) {
        for (;;) {
            fd_set fds;
            struct timeval tv;
            int r;

            FD_ZERO (&fds);
            FD_SET (fd, &fds);

            /* Timeout. */
            tv.tv_sec = 2;
            tv.tv_usec = 0;

            r = select (fd + 1, &fds, NULL, NULL, &tv);

            if (-1 == r) {
                if (EINTR == errno)
                    continue;

                errno_exit ("select");
            }

            if (0 == r) {
                fprintf (stderr, "select timeout\n");
                exit (EXIT_FAILURE);
            }

			if (read_frame ())
                break;
	
			/* EAGAIN - continue select loop. */
        }
    }
}

static void stop_capturing(void)
{
    enum v4l2_buf_type type;

	switch (io) {
	case IO_METHOD_READ:
		/* Nothing to do. */
		break;

	case IO_METHOD_MMAP:
	case IO_METHOD_USERPTR:
		type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

		if (-1 == xioctl (fd, VIDIOC_STREAMOFF, &type))
			errno_exit ("VIDIOC_STREAMOFF");

		break;
	}
}

static void start_capturing(void)
{
    unsigned int i;
    enum v4l2_buf_type type;

	switch (io) {
	case IO_METHOD_READ:
		/* Nothing to do. */
		break;

	case IO_METHOD_MMAP:
		for (i = 0; i < n_buffers; ++i) {
            struct v4l2_buffer buf;

            CLEAR (buf);

            buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
            buf.memory      = V4L2_MEMORY_MMAP;
            buf.index       = i;

            if (-1 == xioctl (fd, VIDIOC_QBUF, &buf))
                errno_exit ("VIDIOC_QBUF");
		}
		
		type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

		if (-1 == xioctl (fd, VIDIOC_STREAMON, &type))
			errno_exit ("VIDIOC_STREAMON");

		break;

	case IO_METHOD_USERPTR:
		for (i = 0; i < n_buffers; ++i) {
            struct v4l2_buffer buf;

            CLEAR (buf);

            buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
            buf.memory      = V4L2_MEMORY_USERPTR;
			buf.index       = i;
			buf.m.userptr	= (unsigned long) buffers[i].start;
			buf.length      = buffers[i].length;

			if (-1 == xioctl (fd, VIDIOC_QBUF, &buf))
                errno_exit ("VIDIOC_QBUF");
		}

		type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

		if (-1 == xioctl (fd, VIDIOC_STREAMON, &type))
			errno_exit ("VIDIOC_STREAMON");

		break;
	}
}

static void
uninit_device(void)
{
    unsigned int i;

	switch (io) {
	case IO_METHOD_READ:
		free (buffers[0].start);
		break;

	case IO_METHOD_MMAP:
		for (i = 0; i < n_buffers; ++i)
			if (-1 == munmap (buffers[i].start, buffers[i].length))
				errno_exit ("munmap");
		break;

	case IO_METHOD_USERPTR:
		for (i = 0; i < n_buffers; ++i)
			free (buffers[i].start);
		break;
	}

	free (buffers);
}

static void init_read(unsigned int buffer_size)
{
    buffers = calloc (1, sizeof (*buffers));

    if (!buffers) {
        fprintf (stderr, "Out of memory\n");
        exit (EXIT_FAILURE);
    }

	buffers[0].length = buffer_size;
	buffers[0].start = malloc (buffer_size);

	if (!buffers[0].start) {
        fprintf (stderr, "Out of memory\n");
        exit (EXIT_FAILURE);
	}
}

static void init_mmap(void)
{
	struct v4l2_requestbuffers req;

    CLEAR (req);

    req.count               = 4;
    req.type                = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    req.memory              = V4L2_MEMORY_MMAP;

	if (-1 == xioctl (fd, VIDIOC_REQBUFS, &req)) {
        if (EINVAL == errno) {
            fprintf (stderr, "%s does not support "
                     "memory mapping\n", dev_name);
            exit (EXIT_FAILURE);
        } else {
            errno_exit ("VIDIOC_REQBUFS");
        }
    }

    if (req.count < 2) {
        fprintf (stderr, "Insufficient buffer memory on %s\n",
                 dev_name);
        exit (EXIT_FAILURE);
    }

    buffers = calloc (req.count, sizeof (*buffers));

    if (!buffers) {
        fprintf (stderr, "Out of memory\n");
        exit (EXIT_FAILURE);
    }

    for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
        struct v4l2_buffer buf;

        CLEAR (buf);

        buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        buf.memory      = V4L2_MEMORY_MMAP;
        buf.index       = n_buffers;

        if (-1 == xioctl (fd, VIDIOC_QUERYBUF, &buf))
            errno_exit ("VIDIOC_QUERYBUF");

        buffers[n_buffers].length = buf.length;
        buffers[n_buffers].start =
            mmap (NULL /* start anywhere */,
                  buf.length,
                  PROT_READ | PROT_WRITE /* required */,
                  MAP_SHARED /* recommended */,
                  fd, buf.m.offset);

        if (MAP_FAILED == buffers[n_buffers].start)
            errno_exit ("mmap");
    }
}

static void init_userp(unsigned int buffer_size)
{
	struct v4l2_requestbuffers req;
    unsigned int page_size;

    page_size = getpagesize();
    buffer_size = (buffer_size + page_size - 1) & ~(page_size - 1);

    CLEAR (req);

    req.count               = 4;
    req.type                = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    req.memory              = V4L2_MEMORY_USERPTR;

    if (-1 == xioctl (fd, VIDIOC_REQBUFS, &req)) {
        if (EINVAL == errno) {
            fprintf (stderr, "%s does not support "
                     "user pointer i/o\n", dev_name);
            exit (EXIT_FAILURE);
        } else {
            errno_exit ("VIDIOC_REQBUFS");
        }
    }

    buffers = calloc(4, sizeof (*buffers));

    if (!buffers) {
        fprintf (stderr, "Out of memory\n");
        exit (EXIT_FAILURE);
    }

    for (n_buffers = 0; n_buffers < 4; ++n_buffers) {
        buffers[n_buffers].length = buffer_size;
        buffers[n_buffers].start = memalign (/* boundary */ page_size,
                                             buffer_size);

        if (!buffers[n_buffers].start) {
            fprintf (stderr, "Out of memory\n");
            exit (EXIT_FAILURE);
		}
    }
}

static void init_device(void)
{
    struct v4l2_capability cap;
    struct v4l2_cropcap cropcap;
    struct v4l2_crop crop;
    struct v4l2_format fmt;
	unsigned int min;

    if (-1 == xioctl (fd, VIDIOC_QUERYCAP, &cap)) {
        if (EINVAL == errno) {
            fprintf (stderr, "%s is no V4L2 device\n",
                     dev_name);
            exit (EXIT_FAILURE);
        } else {
            errno_exit ("VIDIOC_QUERYCAP");
        }
    }

    if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
        fprintf (stderr, "%s is no video capture device\n",
                 dev_name);
        exit (EXIT_FAILURE);
    }

	switch (io) {
	case IO_METHOD_READ:
		if (!(cap.capabilities & V4L2_CAP_READWRITE)) {
			fprintf (stderr, "%s does not support read i/o\n",
                     dev_name);
			exit (EXIT_FAILURE);
		}

		break;

	case IO_METHOD_MMAP:
	case IO_METHOD_USERPTR:
		if (!(cap.capabilities & V4L2_CAP_STREAMING)) {
			fprintf (stderr, "%s does not support streaming i/o\n",
                     dev_name);
			exit (EXIT_FAILURE);
		}

		break;
	}

    /* Select video input, video standard and tune here. */

	CLEAR (cropcap);

    cropcap.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

    if (0 == xioctl (fd, VIDIOC_CROPCAP, &cropcap)) {
        crop.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        crop.c = cropcap.defrect; /* reset to default */

        if (-1 == xioctl (fd, VIDIOC_S_CROP, &crop)) {
            switch (errno) {
            case EINVAL:
                /* Cropping not supported. */
                break;
            default:
                /* Errors ignored. */
                break;
            }
        }
    } else {	
        /* Errors ignored. */
    }


    CLEAR (fmt);

    fmt.type                = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    fmt.fmt.pix.width       = 640; 
    fmt.fmt.pix.height      = 480;
    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUYV;
    fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;

    if (-1 == xioctl (fd, VIDIOC_S_FMT, &fmt))
        errno_exit ("VIDIOC_S_FMT");

    /* Note VIDIOC_S_FMT may change width and height. */

	/* Buggy driver paranoia. */
	min = fmt.fmt.pix.width * 2;
	if (fmt.fmt.pix.bytesperline < min)
		fmt.fmt.pix.bytesperline = min;
	min = fmt.fmt.pix.bytesperline * fmt.fmt.pix.height;
	if (fmt.fmt.pix.sizeimage < min)
		fmt.fmt.pix.sizeimage = min;

	switch (io) {
	case IO_METHOD_READ:
		init_read (fmt.fmt.pix.sizeimage);
		break;

	case IO_METHOD_MMAP:
		init_mmap ();
		break;

	case IO_METHOD_USERPTR:
		init_userp (fmt.fmt.pix.sizeimage);
		break;
	}
}

static void
close_device                    (void)
{
    if (-1 == close (fd))
        errno_exit ("close");

    fd = -1;
}

static void open_device(void)
{
    struct stat st; 

    if (-1 == stat (dev_name, &st)) {
        fprintf (stderr, "Cannot identify '%s': %d, %s\n",
                 dev_name, errno, strerror (errno));
        exit (EXIT_FAILURE);
    }

    if (!S_ISCHR (st.st_mode)) {
        fprintf (stderr, "%s is no device\n", dev_name);
        exit (EXIT_FAILURE);
    }

    fd = open (dev_name, O_RDWR /* required */ | O_NONBLOCK, 0);

    if (-1 == fd) {
        fprintf (stderr, "Cannot open '%s': %d, %s\n",
                 dev_name, errno, strerror (errno));
        exit (EXIT_FAILURE);
    }
}

static void usage(FILE *fp, int argc, char **argv)
{
    fprintf (fp,
             "Usage: %s [options]\n\n"
             "Options:\n"
             "-d | --device name   Video device name [/dev/video]\n"
             "-h | --help          Print this message\n"
             "-m | --mmap          Use memory mapped buffers\n"
             "-r | --read          Use read() calls\n"
             "-u | --userp         Use application allocated buffers\n"
             "",
             argv[0]);
}

static const char short_options [] = "d:hmru";

static const struct option
long_options [] = {
    { "device",     required_argument,      NULL,           'd' },
    { "help",       no_argument,            NULL,           'h' },
    { "mmap",       no_argument,            NULL,           'm' },
    { "read",       no_argument,            NULL,           'r' },
    { "userp",      no_argument,            NULL,           'u' },
    { 0, 0, 0, 0 }
};

int main(int argc, char **argv)
{
    dev_name = "/dev/video";
	save_fd = fopen("test.yuv", "w");

    for (;;) {
        int index;
        int c;
                
        c = getopt_long (argc, argv,
                         short_options, long_options,
                         &index);

        if (-1 == c)
            break;

        switch (c) {
        case 0: /* getopt_long() flag */
            break;

        case 'd':
            dev_name = optarg;
            break;

        case 'h':
            usage (stdout, argc, argv);
            exit (EXIT_SUCCESS);

        case 'm':
            io = IO_METHOD_MMAP;
			break;

        case 'r':
            io = IO_METHOD_READ;
			break;

        case 'u':
            io = IO_METHOD_USERPTR;
			break;

        default:
            usage (stderr, argc, argv);
            exit (EXIT_FAILURE);
        }
    }

    open_device ();

    init_device ();

    start_capturing ();

    mainloop ();

    stop_capturing ();

    uninit_device ();

    close_device ();

	fclose(save_fd);

    exit (EXIT_SUCCESS);

    return 0;
}
